As others have noted, there has been a decrease in the sale of SUVs, especially Hummers. For which I'm grateful--no, actually, gleeful. I live in an urban area and see those dinosaurs everywhere.
IMHO, high gas prices are the only reason people are starting to pay attention to what they drive. I'm not a libertarian, but maybe this is the way it should be. Jimmy Carter asked Americans to conserve, and he was laughed at. Most Americans care about their wallets, nothing else.
So I say, at the risk of being attacked by all, let the prices rise even more!